[llvm] [MachO] Detect overflow in section offset. (PR #98685)

[Eli Friedman via llvm-commits]

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@@ -277,6 +277,8 @@ void MachObjectWriter::writeSection(const MCAssembler &Asm,
     W.write<uint32_t>(VMAddr);      // address
     W.write<uint32_t>(SectionSize); // size
   }
+  if (!isUInt<32>(FileOffset))
+    report_fatal_error("Cannot encode offset of section");
   W.write<uint32_t>(FileOffset);
 
   W.write<uint32_t>(Log2(Section.getAlign()));
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efriedma-quic wrote:

The point of the early return would be to avoid duplicate error messages?  That makes sense, I guess.

https://github.com/llvm/llvm-project/pull/98685